Annual report pursuant to Section 13 and 15(d)

Stock Compensation - Additional Information (Detail)

v3.3.1.900
Stock Compensation - Additional Information (Detail) - USD ($)
$ in Thousands
12 Months Ended
Dec. 31, 2015
Dec. 31, 2014
Dec. 31, 2013
Apr. 16, 2007
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Recognized compensation expense $ 18,300 $ 8,700 $ 2,400  
Income tax benefits 8,000 1,400 $ 500  
Unrecognized compensation cost related to nonvested common shares $ 33,000      
Weighted average period for recognition of cost 1 year 10 months 24 days      
Total fair value of shares vested $ 13,100 $ 1,900    
Percentage of price of common stock purchased 85.00%      
Proceeds from issuance of common stock under the employee stock purchase plan, Shares 223,892 306,459 447,771  
Proceeds from issuance of common stock under the employee stock purchase plan $ 4,318 $ 3,363 $ 2,614  
Minimum [Member]        
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Vesting period of shares from the date of grant 1 year      
Maximum [Member]        
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Vesting period of shares from the date of grant 4 years      
2007 Plan [Member]        
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Number of shares reserved for issuance       22,500,000
Number of shares that remain available for grant 11,108,643      
Equity Incentive Plan [Member]        
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Number of shares reserved for issuance 0      
2008 ESPP [Member]        
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Number of shares reserved for issuance       9,000,000
Maximum percentage of employee's compensation to purchase common stock 15.00%